We consider the interference signals follow the Rayleigh distribution, i.e., \( {h_{I,k,j}} \sim {\rm Rayleigh} \left( {\eta _{k}}\right)\) . Let \(Y \triangleq \sum \limits _{j = 1}^{{N_{Ik}}} {h_{I,k,j}^2}\) . Because the sum of \(N_{Ik}\)  i.i.d. Rayleigh-fading signals have a Nakagami-\(m\)  distributed signal amplitude with \(m=N_{Ik}\) , the PDF and CDF expressions of \(\Vert \mathbf {h}_{k}\Vert ^2\)  can be written as [1]}.
\(f_{Y}\left( y \right) = \frac{{{y^{N_{Ik} - 1}}}}{{\eta _{k}^{N_{Ik}}{\Gamma \!\left( {{N_{Ik}}} \right)}}}\exp \!\left( { - \frac{y}{{{\eta _{k}}}}} \right),\) 
